Pump speed controlling and unloading means



Nov. 16, 1954 w. w. PAGET 2,694,519

PUMP SPEED CONTROLLING AND UNLOADING MEANS Filed March 3. 19 50 3SheetQ-Sheet l :1 I o i R W272 WPa get 14 ziorney Nov. 16, 1954 w. w.PAGET PUMP SPEED CONTROLLING AND UNLOADING MEANS Filed Malrch 3, 1950 3Sheets-Sheet 3 i fizvenzor: 327 4 VVUZ 57 5 'W' V Hzfomey United StatesPatent'Ofiice 2,694,519 Patented Nov. 16, 1954 PUMP SPEED CONTROLLINGAND UNLOADING MEANS Win W. Paget, Michigan City, Ind., assignor to JoyManufacturing Company, Pittsburgh, Pa., a corporation of PennsylvaniaApplication March 3, 1950, Serial No. 147,354

20 Claims. (Cl. 230-4) My invention relates to controlling apparatus,and more particularly to apparatus for automatically controlling thespeed and the loading and unloading of pumps-particularly aircmpressors-in accordance with pump discharge pressure variations.

In the operation of internal combustion engine driven compressors it isdesirable: first, that while the compressor discharge pressure is in thedesired range-for example, 88 to 93 p. s. i. gauge-the speed of thecompressor be controlled generally inversely to the pressure, so that asfar as possible the compressor may be operated continuously and in sucha way as to maintainthe discharge pressure within the chosen limitsmentioned merely by variation of its speed; second, that, if the demandfor air be so low that even at the lowest normal operating speed thedischarge pressure cannot be kept from rising above the chosen upperlimit, then, after operation at such lowest normal operating speed untilthe discharge pressure exceeds the chosen upper limit by a predeterminedsubstantial amountfor example, seven pounds-the compressor be unloadedand be slowed down to a substantially lower idling speed; third, thatthe compressor then be operated unloaded at such lower idling speeduntil the discharge pressure falls back at least substantially saidpredetermined amount-in the example, 7 p. s. i.and back to the upperlimit of the chosen pressure range and then be brought back up to thelowest normal loaded operating speed and reloaded; and fourth, thatthere then be either (a) a gradual speeding up of the compressor if thecompressor discharge pressure continues to fall, or, (b) operation atsaid lowest normal operating speed if compressor discharge pressureremains constant or (c) a return to unloaded condition and a renewedslowing down to an idling speed if the compressor discharge pressureagain builds up the predetermined amount above mentioned. In such asystem it is desirable that the controlling devices be as simple aspossible, that they be adjustable to all the critical pressures in asimple manner, that, as fully as possible, the controls be under theregulation of a minimum number of compressor discharge pressureresponsive devices and use a minimum number of pilot mechanisms, andthat the control mechanism be so arranged that adjustments of certain ofthe critical pressures need not affect others of such pressures.

To meet the objective set forth, I prefer to employ according to apreferred embodiment of the present invention, a primary controlmechanism which includes a pressure responsive element of relativelysubstantial area, subjected on one side to the pressure which is to becontrolled (compressor discharge pressure) and on its other side to apressure which is automatically prevented from exceeding a value whichis a predetermined amount less than the lower limit of the desiredloaded working range of the compressor. Desirably, means is providedwhereby the pressure may be maintained on the last mentioned side ofsaid pressure responsive element and may be increased or diminishedthrough a single adjustment whereby the working pressure range of thecompressor may be readily adiusted. Desirably, moreover, means isprovided whereby the pressure on the last mentioned side of the pressureresponsive element may be bled off at will. Desirably, the pressureresponsive element acts on another element which is movable to effect areduction in the operating speed of the compressor as compressordischarge pressure increases and which,

uponthe attainment thereof .to .a predetermined position of saidpressure responsive element, can be moved no further by the latter, suchposition corresponding to the desired minimum loaded operating speed ofthe compressor.

Desirably, the structure of the device includes another pressureresponsive element subjected to compression discharge pressure andcooperating with the first pressure responsive element in the formationof an expansible chamber communicating with the compressor discharge,said second pressure responsive element movable to effect both unloadingof the compressor and further movement of the element which is movableto effect a reduction in the operating speed of the compressor, so as tobring the compressor down to an idling speed, said second pressureresponsive element being subjected on its side opposite the onesubjected to compressor discharge pressure to a pressure which isautomatically prevented from exceeding a value which is a predeterminedamount less than the value at which unloading of the compressor andoperation of the latter at an idling speed are desired to be effected.Desirably, the second pressure responsive element operates on a pilotvalve mechanism which controls both unloading apparatus for thecompressor and a device for acting on the element movable to effect areduction in the operating speed of the compressor. Desirably too thestructure of the pilot valve mechanism is such that a reduction incompressor discharge pressure substantially equal in amount to thepredetermined increase between the start and finish of movement of thesecond pressure responsive element in the pilot valve moving directionwill occur before the pilot valve will operate to effect speeding up andreloading of the compressor. Desirably, the connection between theelement movable to effect a reduction in the operating speed of thecompressor and the control mechanism of the compressor will include amechanically adjustable mechanism enabling manual control of compressorspeed without alteration of what may be called the fixed adjustment ofthe apparatus.

It is an object of the invention to provide an improved controllingmechanism for effecting variation in the speed of drive of a compressorand to control the loading and unloading of the latter. It is anotherobject to provide an improved compressor controlling apparatuspossessing the characteristics heretofore set forth. It is still afurther object of the invention to provide an improved apparatusincorporating the features hereinbefore mentioned. It is still anotherobject of the invention to provide control mechanism of the charactermentioned having improved means for varying the several criticaloperating characteristics of the compressor which it controls. It isstill another object to provide an improved compressor controllingapparatus incorporating a plurality of pressure responsive elementssubjected on adjacent sides to full compressor discharge pressure, andwith separately adjustable means for subjecting the sides thereof whichare not subjected to full compressor discharge pressures to different,independently adjustable opposing pressures. Still another object of theinvention is to provide an improved internal combustion engine drivenpumping apparatus having improved speed controlling and regulatingmechanism associated therewith. Other objects and advantages of theinvention will hereinafter more fully appear.

In the accompanying drawings, in which for purposes of illustration oneillustrative embodiment of my invention is shown,

Fig. 1 is a fragmentary view of a diesel engine with which theillustrative embodiment of a control mechanism according to one aspectof my invention is associated.

Fig. 2 is a left hand view of the specific pressure responsivecontrolling apparatus shown in Fig. 1.

Fig. 3 is a right hand view of the same apparatus.

Fig. 4 is a longitudinal vertical section through the apparatus, thesection being taken on a plane of the line -'-l4 of Fig. 2.

Fig. 5 is a sectional view on the plane of the line 55 of Fig. 4.

Fig. 6 is an enlarged detailed fragmentary section on the plane of theline 6-6 of Fig. 4.

Fig. 7 is a detail section on an enlarged scale on the plane of line 77of Fig. 4.

Fig. 8 is a detail fragmentary section on the plane of the line 88 ofFig. 4, on an enlarged scale.

Fig. 9 is an axial sectional view through a compressor cylinder headshowing inlet and discharge valve mechanisms and unloading devices.

Fig. 10 is a detailed sectional view on an enlarged scale on the sameplane as Fig. 4.

Fig. 11 is a diagrammatic view showing the controlling apparatus with areceiver and compressor unloading means.

Referring to the drawings:

It will be noted that my improved controlling mechanism is shown appliedto a diesel engine drive compressor. In following the ensuingdescription, it should be borne in mind that diesel engines are providedwith builtin mechanisms for controlling the injection of fueL. In onewell-known form of such an invention, in conjunction with which I havechosen to illustrate my invention in its illustrative embodiment, thefuel injection pump plunger is turned by a pinion connected to it and bya rack to one end of which a speed governor controlling shaft isconnected. The other end of the rack is linkconnected to a lever, hereinindicated at 12, to which a spring 13 is connected and the tension ofthe spring is adjustable to eifect a change in the engine speed. Thespring tension is adjusted by varying the position of a lever 14 towhich the other end of the spring 13 is connected. When the rack ismoved back and forth by the opposed actions of the governor (not shown)and of the spring 13, the fuel injection pump plunger is turned and theamount of fiuid injected is varied. This mechanism acts on all of theinjection pumps simultaneously so that an equal and correct amount offuel is delivered to each cylinder. It is unnecessary to illustrate thiswellknown commercial mechanism other than to the extent of the foregoingdescription. Obviously, other fuel injection control mechanisms may becontrolled by the basic control mechanism of this embodiment of myinvention.

For controlling the adjustment of the lever 14, I have provided theimproved control apparatus illustratively shown in side elevation inFig. 1; in opposite end elevations in Figs. 2 and 3, in section in Figs.4 and and in diagrammatic association with other elements of a gaseousfluid pumping system in Fig. 11, this control apparatus being generallydesignated 16.

The unit 16 is adapted to cause the engine to operate on the order of1400 to 1450 R. P. M. at and below a compressor discharge pressure of 88p. s. i. gauge. As compressor discharge pressure rises above 88 p. s. i.the compressor speed is reduced until at 93 pounds it is 1050 R. P. M.If the compressor discharge pressure rises to 100 pounds unloading iseffected and the compressor speed is cut to an idling speed which maydesirably be in the range of 550 R. P. M. to 700 R. P. M. When thecompressor discharge pressure again falls to 93 pounds, reloadingoccurs, and the speed returns to 1050 R. P. M.

The control unit 16 is shown as made up of three casing sections orelements 21, 22 and 23. The casing element 21 carries at its right handside in Fig. 4 pivotally supported thereon for turning upon a pivotpin25,.a lever 26. This lever has pivotally connected .to it at 27 anotherlever 28, whose position relative to the lever 26 is controllable by amechanically adjustable screw, nut and slot connection 29. (See Fig. 8.)The'lever 28 has a projecting arm 30, which is pivotally connected as at31 with a link 32 which is in turn pivotally connected as at 33 with anarm 34 rigidly connected with the lever arm 14 previously mentioned. Itwill be understood that swinging movements of the lever 26 upon thepivot mounting 25 will, if the screw, nut and slot connection 29 istight, effect swinging movements of the bell crank lever 14, 34.Movement of the lever 26 clockwise about its pivot 25, reduces thetension of the spring 13, thus causing slowing down of the dieselengine. It will also be understood that by loosening the screw, nut andbolt connection 29, the lever 28 may be swung independently of the lever26 and thus provide manual change in the speed of theengine when it isdesired.

A relatively long, fiat-rate spring 40 is supported between a recessedbracket portion 41 on the casing element 21 and an adjustable screw 42provided with a lock nut 43 and carried by the lower end of the lever 26and adapted to engage at 44 a spring follower member 45. The forceexerted by the spring 40 in any angular position of the lever 26 mayevidently be varied by varying the adjustment of the screw 42 in thelower end of the lever 26.

The distance which the upper end of the lever 26 can move to the left inFig. 4-and thus the maximum operating speed of the diesel engine whichdrives the compressor--is controllable by an adjustable screw 50 havinga lock nut 51 and mounted in the upper end 52 of the lever 26 andadapted to engage an abutment surface 57, later again referred to. Itwill be noted that, in the absence of other forces, the spring 40 willmaintain the lever 26 in such a position that the end of the screw 50will engage the abutment surface 57.

It has been noted that the control unit 16 is shown as made up of threecasing elements 21, 22 and 23. The casing element 22 is generallyannular and has an inner periphery 64 and end surfaces 65 and 66.Sections 21 and 23 are adapted 'to clamp between them and the surfaces65 and 66 respectively, flexible metallic diaphragm elements 67 and 68.The element- 21 has an annular surface 69 engageable with a planeperipheral portion 70 of the diaphragm 67 and pressing this portionagainst the surface 65. correspondingly, casing element 23 has anannularsurface 71 engaging an annular plane portion 72 of the diaphragm 68 andpressing the latter, in the assembled relation of the parts, against thesurface 66. As a result of this construction there is provided a chamber75 between the diaphragms 67 and 68, this chamber being bounded by theadjacent surfaces 77 and 78 respectively of the diaphragms 67 and 68 andby the surface 64. A passage 80, with which conduit 81, later furthermentioned, communicates, opens radially through the section 22 and intothe chamber 75. A radial passage 82 closed at its outer end by a plug83, opens from the chamber 75 as shown in Fig. 5. A passage 84, formedin the casing section 21, connects the radial passage 82 in the section22 with another and longer radially extending passage 85 in the casingsection 21. The outer end of the radial passage 85 is closed by a plug86. It may be noted that the portion of the passage 84 which extendsthrough the diaphragm 67, is surrounded by a sleeve or bushing 87,seated in part in the recess 88 in the casing section 22, and in part ina bore 89 formed in the casing section 21. Similar arrangements are usedwherever passages pass through openings in the diaphragms and thisdetail of construction will not be mentioned in connection with othersuch passages.

The casing section 21 is recessed at 90 at the side next to thediaphragm 67. This casing element also has a bore 92 coaxial with therecess 90, and with the bore 92 the radial passage 85 communicates. Asmaller bore 93 is arranged coaxial with the bore 92, and against ashoulder 94 formed at the junction of said bores an appropriate packingring 95 is arranged. The end of the bore 92 towards the chamber 90 isprovided with a threaded plug 96 and a guide bushing 97 is arranged inthe outer end of the bore 93. The plug 96 is traversed by an opening 99and through this opening and through the bore 100 of the bushing 97,there extends an operating rod 102 which carries at its inner end aplate 103 which is engaged by a'flat external portion 104 of thediaphragm 67, and which is adapted upon predetermined movement to theright in Figs. 4 and 5, to engage the end of bushing 96. The outer endof the operating rod 102 is adapted to engage an adjustable screwelement 105, provided with a lock nut 106 and extending through athreaded opening 107 in the lever 26. It will be evident that thediaphragm 67 is capable of exerting a limited control upon the angularposition of the lever 26, through the operating rod 102a control which,so far as further movement of the lever is concerned, is terminated whenthe plate 103 engages the face of the plug 96. The control rod 102 isslightly smaller in diameter than the internal diameter of the opening99, with the result that there is a constant restricted communicationbetween the chamber 75 and the chamber 90, this communication beingmaintained even when the plate 103 engages the plug 96 by reason of theradial grooving of the end of the latter, as at 110. The chamber 90 isin constant communication through an opening 111 with a chamber 112,formed in the casing element 21. The chamber 112 has arranged radiallyoutwardly of it an enlarged bore 114, in which there' is threadedlysecured a ball valve seat and valve housing member115. The threaded connection 116 enables the member 115 to be pressed tightly against awasher 117 supported on a shoulder 118 at the junction of the chamber112 and the bore 114. The member 115 contains a chanber 120 in whichthere is a ball valve 121. The ball valve is engageable with a seat 122surrounding a port 123 which, when the ball 121 is lifted from its seat,provides communication between the chamber 112 and the chamber 120. Thechamber 120 communicates through radial passages 125 with an annularspace 126, between the member 115 and the peripheral wall of the bore114, and the annular space 126 is vented to atmosphere through anopening 127. Thus, the chamber 120 is constantly vented to atmosphere.The ball 121 is pressed to its seat by a follower 130 having a stem 131and received in an adjustable follower chamber-providing member 133. Theposition of the follower chamber providing member is variable by reasonof its threaded connection 134 with the member 115 and a lock nut 135 isadapted to hold the parts in adjusted position. A spring 136 is enclosedWithin the follower chamber providing member 133 and engages thefollower 138. The tension of the spring may be varied by changing therelation of the follower chamber providing member to the member 115. Theloading of the ball valve 121 will be described more fully later.

A passage 138 opens out of the radial passage 80 and extends to the leftin Fig. 4 and is connected to a passage 139, which communicates with apassage 140 extending radially of the casing section 23. The passage 140terminates in a reduced portion 141 and opens into a chamber 142. Thechamber 142 constitutes a portion of a stepped bore generally designated143, which, though it is broken up by a plug, a packing, a bushing, anda valve seat member, and closed at its outer end by another plug, may besaid to extend completely through the casing element 23 along the axesof the latter. Starting at the left hand end of the casing element 23,as viewed in Fig. 4, it will be observed that there is, forming aportion of the bore 143, an internally threaded, relatively largechamber 144 closed by a threaded plug 145 and communicating with aslightly smaller bore or chamber 146 forming another portion of the bore143. There is a counterbore 147 between the chamber 144 and the chamber146. Within the chamber 146 there is mounted a chambered valve seatelement 148, and a valve, herein a ball valve 149, is adapted to seat onthe valve seat 150, formed on the valve seat element 148, and this valveis normally pressed towards said seat -by a spring 151, housed within arecess 152 formed in the threaded plug 145. The valve seat element 148is bored as at 155 so that the reduced portion 156 of a valve stem 157can extend and move through it. The valve stem extends through a smallerchamber 158 adjacent the valve seat member 148 and the chamber 158 isvented to atmosphere through a passage 159. It may be noted that aconduit 160, of which more will be said shortly, communicates through apassage 161 with the chamber 146. The valve stem 157 extends through,and is guided by a bushing 162 mounted in the bore 143, and also extendsthrough a packing 163 mounted in a slight enlargement 164 of the bore143. To the right of the packing there is a larger bore 166 in which athreaded plug 167 is mounted. This plug is traversed by an axial bore168 which also serves as a guide for the stem 157, but its guiding is aloose one since there is provided a small circumferential clearance 169around the valve stem so that the chamber 142, communicates restrictedlywith a large chamber 170 to the left of the diaphragm 68 in Figs. 4 and5. The stem 157 carries an enlarged plate member 171 which is engageablewith a large central portion 172 of the diaphragm 68, between whichcentral portion and the plane portion 72 there is an annular flexibleportion 173. It may be noted that the diaphragm 67 is of correspondingconstruction, having also a flexible portion 176 connecting its centralportion and its peripheral portion 70. A spring 178 surrounds the stem157 and acts between the threaded plug 167 and the plate 171, thisspring compensating, at the pressure normally maintained at the oppositesides of the diaphragm 68, for the reduction in pressure area at theleft side of the diaphragm occasioned by the valve stem 157. It may nowbe noted that there is communication between the chamber 75 and thechamber 170 through the opening 138, passage 139, passage 140, passageportion 141, chamber 142 and the annular clearance 169.

The pressure maintained within the chamber is determined by the seatingof a relief valve mechanism 180. This mechanism includes a relief valveproper 181, herein shown as the ball type, received in a chamberformingbore 182 in the casing portion 23. Bore 182 is closed at its outer endby a threaded plug 183, housing within a chamber 184 thereof a spring185 which presses the valve 181 towards a valve seat 186 formed on ahollow valve seat member 187 having a chamber 188 therein. The chamber188 communicates through a passage 189 with the chamber 170. A passage191 opens out of the bore or chamber 182 and is provided with a manuallycontrollable valve 192 openable to vent to atmosphere the passage 191and the chamber 182. The passage 191 is connected by another passage 193formed in part in each of the casing elements 23, 22 and 21 and by afurther passage 194, with the chamber 90.

The interior of the chambered valveseat member 148 is connected by apassage 200 with a chamber 201 in the casing element 23. Chamber 201 isconnected by a passage 202, made up of angularly related portions 203,204 and 205, in the casing element 23, a passage portion 206 in thecasing element 22, and a passage portion 207 in the casing element 21,with a bore 209 formed in the casing element 21, and arranged parallelwith the axis of the operating rod 102. A liner member 211 having a headportion 212 upon which the surface 57 is formed, is threaded into thebore 209 and has a bore 213 providing a cylinder C in which a suitablypacked piston 214 is reciprocable. The stem or rod 215 of the piston 214extends outwardly through a bushing 216 carried by the member 211 and isengageable with the end of a screw 218 having a lock nut 219 andthreaded through the lever member 26 between the screw 105 and the screw50. The chamber 201 is closed by a compound plug including an outerelement 221 threaded into the casing member 23 and an inner member 222threaded into the outer plug member. There is another opening 225leading from the side of the chamber 201. This opening is connected by aconduit 226, as shown in Fig. 11, with the unloading devices for thecompressor. When one unit is to be used to control several engine drivencompressors, the inner elements 222 of the compound plugs of the unitsassociated with the compressors to be controlled (the slave compressors)will be screwed down into threads 227 formed in the inner ends of thechambers 201, and thus in the slave units the respective chambers 201will be cut off from communication with the interiors of the valve seatmembers 148, while the chambers 201 on the slave units will stillcontinue to communicate with the unloading and idling devices. Theremoval of the element 222 from the master unit, and the connection ofthe bores of the several outer elements 221 by suitable conduit meanswill permit the master unit to control the unloading and idling of allof the units, while each will be controlled as to slow downindividually.

The power shaft of the engine is operatively connected by means notshown to a compressor of which one piston is shown at 228 in Fig. 9; andthe engine effects reciprocation of the piston 228 in a cylinder bore229 formed in a cylinder block 230. It will be understood that othercompressor cylinders containing pistons connected for reciprocation bythe power shaft may be provided if desired, and that such willordinarily be used. Fluid is admitted through an intake passage 231 andpast an inlet valve 232 to the cylinder bore 229, where it is compressedand whence it is discharged past a discharge valve 23-4 to a passage 235which is connected by suitable connections, not shown, to a receiver R.The cylinder 230 has a head 236 connected thereto by bolts 237, andattached to the head as by bolts 238 is a member 239 having a chamber240 which receives a piston 241 having connected to it a plate 242. Rodsor fingers 243 connected to the plate 242 extend through openings in thecylinder head to engage the inlet valve 232, for unseating the latterand effecting an unloading of the compressor cylinder When the piston241 is subjected to pressure fluid. The piston 241 is normally held inits raised position by a spring 244 and is adapted to be forced to itslower position against the action of the spring 244 by pressure fluidsupplied to the chamber 240 through a conduit 245. The conduit 245 isconnected with the conduit 226.

The mode of operation of the invention will be readily understood. Ithas been noted that the arm 30 of the lever 28 is connected by a link 32with an arm 34 which is rigidly connected with the arm 14. Accordingly,clockwise rotation of the lever 28, either about its pivot 27 on thelever 26, or with the lever 26 about the pivot 25 of the latter, reducesthe resistance offered by the spring 13 in such a manner that the forcesproduced by the governor of the diesel engine at lower engine speedswill be able to overcome the spring 13 in such a manner as to effectslowing down of the diesel engine. When the wing nut 29 is loosened thelever 28 can be swung relative to the lever 26 and provide hand controlof diesel engine speed. By tightening the nut 29 when the lever 28 is inproper relation to lever 26 automatic speed control will be elfected.When the lever 28 is swung as far counter-clockwise about its pivot 27as is permitted by the length of the slot, and when the adjusting screw50 is against abutment surface 57, an adjustment of the tension of thespring 13 corresponding to maximum operating speed will be provided.

The diesel engine will operate at maximum speed when the lever 26 is asfar to the left at its upper end 52 in Fig. 4 as it can move, andaccordingly the adjustment of the stop screw 50 will determine themaximum engine speed and, correspondingly, the maximum speed of thecompressor which the engine drives. The adjusting screw 42 carried atthe bottom of the lever 26 is adapted to vary the force opposed by thespring 40 to the clockwise movement of the lever 26 by the diaphragm. Ithas been noted that the diaphragm 67 is adapted to act through a controlrod 102 upon adjustable screw 105, and it will be appreciated that theminimum speed at which the engine will drive the compressor while thelatter is loaded, will be determined by the adjustment of the screw 105.The adjustment of the screw 218 determines the minimum speed of theengine when the compressor is unloaded.

Certain pressures, which will be understood to be exemplary, may now bereviewed in order that the mode of operation of the apparatus may bemore fully understood. The pressure exerted by the spring 136 will be sopredetermined by adjustment of the member 133 so that the maximumpressure maintainable within the chamber 112 will be 88 pounds. Whencompressor discharge pressure, and accordingly the pressure within thechamber 75, is less than 88 pounds, the pressure in the chamber 112 willof course be less than 88 pounds, but when the pressure within thechamber 75 attains to 88 pounds, pressure in the chamber 112 will alsobe 88 pounds. When the pressure in the chamber 75 goes above 88 poundsthe pressure in the chamber 112 will be maintained at 88 pounds bybleeding of fluid from the chamber past the ball valve 121.

The spring 185 will be so precompressed by adjustment of the plug member183 that the maximum pressure which can be maintained in the chambers188 and 170 will be 93 pounds. Accordingly, when the pressure within thechamber 75 is less than 93 pounds the pressure in the chamber 188 willbe correspondingly less than 93 pounds. When the pressure in the chamber75 equals 93 pounds the pressure in the chamber 188 will be 93 pounds.When the pressure in chamber 75 exceeds 93 pounds, the pressure in thechamber 188 will be held to 93 pounds by the bleeding of pressure fluidpast the ball valve 181 and through the passages 191, 193, 194, chamber90, passage 111, chamber 112, past the ball valve 121, through passages125 and space 126 and out through the passage 127 to atmosphere. Sincethe setting of the ball valve 121 is lower than the setting of the ballvalve 181, the pressure fluid from the chamber 188 will bleed freely toatmosphere when the valve 181 lifts from its seat. The valve 149, due toits loading by the spring 151, and the unbalanced pressure area thereonsubjected to compressor discharge pressure will require the pressure inthe chamber 75 to attain a value of 100 pounds before the force producedby the unbalanced pressure on the diaphragm 68 will unseat the valve 149and admit pressure to the unloading devices of the compressor and to acton the piston 214. When the valve 149 is once unseated there will be sosubstantial an increase in area thereon subjected to compressordischarge pressure that the pressure in the chamber 75 will have to dropoff again on the order of 7 pounds, that isback to 93 pounds-before thevalve will close and vent the chamber to atmosphere through the interiorof valve seat element 148, passage 155, chamber 158, and port 159.

Now let it be assumed that the compressor discharge pressure is 88pounds and that this pressure subsists in the chamber 75 and in thechamber 112. The same pressure will subsist in chamber 188. Under thesecircumstances, the lever 26 will occupy the position shown in Figs. 1and 4 and, the lever 28 being fixed in proper relative position to thelever 26, the compressor will be operating loaded and at its thenmaximum speed, say, on the order of 1400 to 1450 R. P. M. The smallerthe angle between the levers 26 and 28 the higher will be the top enginespeed. If the load-the demand for airis insufficient to use up thecompressed air as fast as it is delivered through the compressordischarge line, compressor discharge pressure will commence to build up,and so the pressure in the chamber 75 will commence to build up. Therewill be no corresponding increase in the pressure in the chamber 112,though there will be a corresponding increase in the chamber 188.Therefore, the diaphragm 67 will commence to move the control rod 102,and, through the abutment of the latter with the adjustable screw 105,the lever 26 will be moved clockwise and a slowing down of thecompressor will be initiated. This slowing down will continue, if thereceiver pressure continues to increase, until the plate 103 engages theplug 96, at which time the speed of the compressor may have been reducedto on the order of 1050 R. P. M. When the pressure in the chamber 75reaches 93 pounds the pressure in the chamber 188 will also reach 93pounds and any further increases of the pressure in the chamber 75, suchas may occur if the air demand is still below the rate of compressed airdelivery even at the reduced speed of operation of the compressor, willresult in cracking from its seat of the ball valve 181 and themaintenance of pressure n the chamber 170 constant at 93 pounds.Subsequent increases in the pressure in chamber 75 will result in adifferential in pressure between that chamber and the chamber 170 andthe exertion of a force towards the left by the diaphragm 68, until,when the pressure differential becomes equal to 7 pounds, with theexample given, the force will be suflicient to unseat the ball valve149. With this ball valve unseated and with the vent passage 155 closedby the valve stem 157, fluid will be delivered to act on the piston 214and also through the passage 225 to the unloading devices of thecompressor and the compressor will not only be unloaded, but be sloweddown an amount corresponding to the position of the lever 26 when thepiston 214 reaches the right hand end of the bore 213. This will resultin operation at an idling speed, and what this will be will bedetermined by the adjustment of the screw 218. Anywhere between, say 500and 700 R. P. M. may be satisfactory.

If there is no demand for air the compressor may continue to operate fora substantial period at the reduced idling speed which corresponds tothe position of the lever 26 attained as a result of the movementtransmitted to the screw 218 by the piston rod 215. If leakage or airdemand commences to reduce the receiver pressure-and the pressure inchamber 75below pounds, there will be a reduction of the force exertedin the left hand direction by the diaphragm 68, but this will beinsufficient to permit reseating of the valve 149 and opening of thevent 159 to atmosphere until the pressure in the chamber 75 falls offapproximately 7 pounds from the maximum value, that is, to 93 pounds,again. When this reduction in pressure has occurred the supply of fluidto the piston 214 and to the unloading device will be interrupted andthese will be vented to atmosphere through the vent port 159. Thecompressor will then be operated loaded at its minimum loaded speed, forthe lever 26 will move counter-clockwise until the screw enages thestill projected stem 102.

If the demand for air is less than its rate of delivery at therelatively low speed of operation of the compressor under theseconditions, the pressure in the chamber 75 will build up again and theremay occur a re-unloading and a re-slowing down to idling speed. On theother hand, if at the slow speed of operation the compressor does notdeliver enough air to meet the demand the pressure in the chamber 75will continue to fall off and as it falls oil. from 93 p. s. i. to 88the diaphragm 67 will progressively be moved to the left ascounter-clockwise movement of the lever 26 is effected by the spring 40and the compressor speed will build up until the quantity of airdelivered equals the air demand and the pressure in the chamber 75ceases to fall. Of course, if the demand is largeso large that even inthe retracted position of the control rod 102, the compressor cannotsupply all the air needed, the pressure in the chamber 75 may continueto fall but the engine speed will not be increased above that whichprevails when the end of the screw 50 contacts the abutment surface57--in the case now assumed, 1450 R. P. M.

From the foregoing description, it will be appreciated that I haveprovided an improved, pressure responsive control mechanism for anengine driven compressor, one particularly adapted for control of adiesel engine driven compressor. The mechanism is a unitary one, itincludes a single chamber supplied with compressor discharge pressureand having a plurality of movable bounding walls one by its movementsgoverning speed variation of the compressor while it operates loaded andthe other controlling both unloading and idling of the compressor. Themovable bounding walls are of relatively large area, but, having theirsides opposed to those on which full compressor discharge pressure actssubjected to relatively high pressures, there is no danger of theirrupture, and yet there are ample operating forces. A device capable ofthe control of a plurality of compressors is provided. The constructionis simple, rugged and efiicacious.

A very great advantage of the control lies in its capacity forcompletely independent.adjustability of the full operating speeds, theminimum normal operating speed, the idling speed and the point ofunloading and reloading.

While there is in this application specifically described one form bothas to apparatus and as to method which the invention may assume inpractice, it will be understood that this form of the same is shown forpurposes of illustration and that the invention may be modified andembodied in various other forms without departing from its spirit or thescope of the appended claims.

What I claim is:

1. A controlling device for an engine driven compressor unit comprising,in combination, an element movable to control engine speed, means forresiliently pressing said member in one direction, and a plurality ofmeans for moving said element in the opposite direction including anelement continuously subjected to compressor discharge pressure andhaving means associated with it for transmitting its motion to saidfirst mentioned element, another element movable by compressor dischargepressure and having means for transmitting its motion to said firstmentioned element, a fourth element subjected to compressor dischargepressure, and a pilot valve controlled by said fourth element andcontrolling the action of compressor discharge pressure on said thirdelement, said second and fourth elements each having a surface facingthe other subjected to compressor discharge pressure.

2. A controlling device for an engine driven compressor unit comprising,in combination, an element movable to control engine speed, means forresiliently pressing said member in one direction, and a plurality ofmeans for moving said element .in the opposite direction including anelement continuously subjected to compressor discharge pressure andhaving means associated with it for transmitting its motion to saidfirst mentioned element, another element movable by compressor dischargepressure and having means for transmitting its motion to said firstmentioned element, a fourth element subjected to compressor dischargepressure and a pilot valve controlled by said fourth element andcontrolling the action of compressor discharge pressure on said thirdelement, said second and fourth elements constituting walls of a commoncompressor discharge pressure supplied chamber.

3. A controlling device for an engine driven compressor unit comprising,in combination, an element movable to control engine speed, means forresiliently pressing said member in one direction. and a plurality ofmeans for moving said element in the opposite direction including anelement continuously subjected to compressor discharge pressure andhaving means associated with it for transmitting its motion to saidfirst mentioned element, another element movable by compressor dischargepressure and having means for transmitting its motion to said firstmentioned element, a fourth element subjected to compressor dischargepressure and a pilot valve controlled by said fourth element andcontrolling the action of compressor discharge pressure on said thirdelement, said second and fourth elements constituting oppositely facingwalls of a common compressor discharge pressure supplied chamber.

-4. A controlling device for an engine driven compressor unitcomprising, in combination, an element movable to control engine speed,means for resiliently pressing said member in one direction, and aplurality of means for moving said element in the opposite directionincluding an element continuously subjected to compressor dischargepressure and having means associated with it for transmitting its motionto said first mentioned element, another element movable by compressordischarge pressure and having means for transmitting its motion to saidfirst mentioned element, a fourth element subjected to compressordischarge pressure and a pilot valve controlled by said fourth elementand controlling the action of compressor discharge pressure on saidthird element, said fourth element also subjected to a superatmosphericfluid pressure less than and independent of variations in compressordischarge pressure during the normal working operating cycle of saiddevice.

5. A controlling device for an engine driven compressor unit comprising,in combination, an element movable to control engine speed, means forresiliently pressing said member in one direction, and a plurality ofmeans for moving said element in the opposite direction including anelement subjected to compressor discharge pressure and having meansassociated with it for transmitting its motion to said first mentionedelement, another element movable by compressor discharge pressure andhaving means for transmitting its motion to said first mentionedelement, a fourth element subjected to compressor discharge pressure anda pilot valve controlled by said fourth element and controlling theaction of compressor discharge pressure on said third element, saidsecond and fourth elements each being subjected to a superatmosphericfluid pressure acting oppositely to compressor discharge pressure andless than and independent of variations in compressor discharge pressureduring the normal working operating cycle of said device.

6. A controlling device for an engine driven compressor unit comprising,in combination, an element movable to control engine speed, means forresiliently pressing said member in one direction, and a plurality ofmeans for moving said element in the opposite direction including anelement continuously subjected to compressor discharge pressure andhaving means associated with it for transmitting its motion to saidfirst mentioned element, another element movable by compressor dischargepressure and having means for transmitting its motion to said firstmentioned element, a fourth element subjected to compressor dischargepressure and a pilot valve controlled by said fourth element andcontrolling the action of compressor discharge pressure on said thirdelement, said second and fourth elements each being subjected to anoppositely acting superatmospheric fluid pressure less than andindependent of variations in compressor discharge pressure during thenormal worklng operating cycle of said device, said fourth mentionedelement having the fluid pressure acting oppositely to compressordischarge pressure thereon greater than the corresponding fluid pressureon said first mentioned compressor discharge pressure subjected element.

7. A controlling device for an engine driven compres sor unitcomprising, in combination, an element movable to control engine speed,means for resiliently pressing said member in one direction, and aplurality of means for moving said element in the opposite directionincluding an element freely subjected on one side to compressordischarge pressure and having means associated with it for transmittingits motion to said first mentioned element, another element movable bycompressor discharge pressure and having means for transmitting itsmotion to said first mentioned element, a fourth element freelysubjected on one side to compressor discharge pressure and a pilot valvecontrolled by said fourth element and controlling the action ofcompressor discharge pressure on said third element, said second andfourth elements having their sides not freely subjected to compressordischarge pressure restrictedly connected therewith, and relief valvemeans for bleeding oft pressure from said other sides, to preclude thesubjection of said last mentioned sides to pressures as high as normalworking compressor discharge pressure.

8. A controlling device for an engine driven compressor unit comprisingin combination, an element movable to control engine speed, means forresiliently pressing said member in one direction, and a plurality ofmeans for moving said element in the opposite direction including anelement freely subjected on one side to compressor discharge pressureand having means associated with it for transmitting its motion to saidfirst mentioned element, another element movable by compressor dischargepressure and having means for transmitting its motion to said firstmentioned element, a fourth element freely subjected on one side tocompressor discharge pressure and a pilot valve controlled by saidfourth element and controlling the action of compressor dischargepressure on said third element, said second and fourth elements havingtheir sides not freely subjected to compressor discharge pressurerestrictedly connected therewith, and relief valve means for bleedingoff pressure from said other sides, to preclude the subjection of saidlast mentioned sides to pressures as high as normal working compressordischarge pressure, the relief valve means associated with said fourthelement having the higher settin 9. a controlling device for an enginedriven compressor unit comprising, in combination, an element movable tocontrol engine speed, means for resiliently pressing said member in onedirection, and a plurality of means for moving said element in theopposite direction including an element freely subjected on one side tocompressor discharge pressure and having means associated with it fortransmitting its motion to said first mentioned element, another elementmovable by compressor discharge pressure and having means fortransmitting its motion to said first mentioned element, a fourthelement freely subjected on one side to compressor discharge pressureand a pilot valve controlled by said fourth element and controlling theaction of compressor discharge pressure on said third element, saidsecond and fourth elements having their sides not freely subjected tocompressor discharge pressure restrictedly connected therewith, andrelief valve means for bleeding off pressure from said other sides, topreclude the subjection of said last mentioned sides to pressures ashigh as normal working compressor discharge pressure, the relief valvemeans associated with said fourth element having the higher setting, andsaid last mentioned relief valve means connected to discharge to theother relief valve means.

10. A controlling device for an unloading means equipped engine drivencompressor unit comprising, in combination, an element movable tocontrol engine speed, means for resiliently pressing said member in onedirection, and a plurality of means for moving said element in theopposite direction including an element subjected to compressordischarge pressure and having means associated with it for transmittingits motion to said first mentioned element, another element movable bycompressor discharge pressure and having means for transmitting itsmotion to said first mentioned element, and means for controlling thesupply and venting of compressor discharge pressure relative to saidthird element including a fourth element subjected to compressordischarge pressure and a pilot valve controlled by said fourth element,said pilot valve device also constituting a controlling device for theunloading means of said unit and said second and fourth elementsconstituting opposite walls of a compressor discharge pressure suppliedchamber.

11. In a controlling device, in combination, a casing having an annularcentral portion and recessed head portions one at each side of saidcentral portion, flexible diaphragms clamped one between each headportion and the side of said annular central portion which is nearerthereto, means for conducting a pressure to be controlled to the spacebetween said diaphragms, means for conducting pressure to the spacesbetween said diaphragms and said recessed head portions, means forbleeding pressure from said last mentioned spaces automatically upon theattainment of the pressure within such spaces to different predeterminedvalues, an operating rod operatively connected with one of saiddiaphragms, a fluid operated operating rod arranged to act in likedirection with said operating rod first mentioned, a control membermovable by said operating rods, a third operating rod operativelyconnected with the other of said diaphragms, and valve means controlledby said third operating rod 12 for controlling the supply and venting offluid for the control of said fluid operated operating rod.

12. In a controlling device, in combination, a casing having an annularcentral portion and recessed head portions one at each side of saidcentral portion, flexible diaphragms clamped one between each headportion and the side of said annular central portion which is nearerthereto, means for conducting a pressure to be controlled to the spacebetween said diaphragms, means for conducting pressure to the spacesbetween said diaphragms and said recessed head portions, means forbleeding pressure from said last mentioned spaces automatically upon theattainment of the pressure within such spaces to different predeterminedvalues, an operating rod operatively connected with one of saiddiaphragms, means for limiting the movement of said rod, a fluidoperated operating rod arranged to act in like direction with, but withgreater travel than, said operating rod first mentioned, a controlmember movable by said operating rods, a third operating rod operativelyconnected with the other of said diaphragms, and valve means controlledby said third operating rod for controlling the supply and venting offluid for the control of said fluid operated operating rod.

13. In a controlling device for a motor driven compressor, incombination, a casing having an annular central portion and recessedhead portions one at each end of said central portion, flexiblediaphragms clamped one between each head portion and the adjacent sideof said annular central portion, a connection on said casing with thespace between said diaphragms for the introduction into said space ofcompressor discharge pressure, means for conducting pressure to thespaces between said diaphragms and said recessed head portions, meansfor bleeding pressure from said last mentioned spaces automatically uponthe attainment of the pressures within such spaces to respectivelydifferent predetermined values, an operating rod operatively connectedwith one of said diaphragms, an operating rod operatively connected withthe other of said diaphragms, valve means controlled by said secondoperating rod, a servo-motor controlled by said valve means and havingan operating rod, and a member adapted to act as a motor speed controlelement, and with which said first and third operating rods coact tocontrol its position.

14. In a controlling device for a motor driven compressor, incombination, a casing having an annular central portion and recessedhead portions one at each end of said central portion, flexiblediaphragms clamped one between each head portion and the adjacent sideof said annular central portion, a connection on said casing with thespace between said diaphragms for the introduction into said space ofcompressor discharge pressure, means for conducting pressure to thespaces between said diaphragms and said recessed head portions, meansfor bleeding pressure from said last mentioned spaces automatically uponthe attainment of the pressures within such spaces to respectivelydifferent predetermined values, an operating rod operatively connectedwith one of said diaphragms, an operating rod operatively connected withthe other of said diaphragms, valve means controlled by said secondoperating rod, a connection on said casing, controlled by said valvemeans, for a conduit connected with compressor unloading means, aservo-motor controlled by said valve means and having an operating rod,and a member adapted to act as a motor speed control element, and withwhich said first and third operating rods coact to control its position.

15. A controlling device. for an engine driven compressor unit foreffecting, through a variation in the tension of a governor spring, acontrol of engine speed, said controlling device comprising a leverswingable to vary the tension of a governor spring, and actuating meansfor said lever including spring means for swinging the same in onedirection and fluid operated means for swinging said lever in theopposite direction, said fluid operated means including a cylinder and apiston therein, and fluid supply means for said cylinder including avalve and operating means therefor including an element having areas atits opposite sides for the action thereon of fluid pressure, means fordelivering compressor discharge pressure freely to one side of saidelement, and means for continuously subjecting the area at the otherside of said element to a fluid pressure less than and independent ofvariations in the compressor discharge pressure during the normaloperation of the unit.

16. A controlling device for an engine driven compressor unit foreffecting, through a variation in the tension of a governor spring, acontrol of engine speed, said controlling device comprising a leverswingable to vary the tension of a governor spring, and actuating meansfor said lever including spring means for swinging the same in onedirection and fluid operated means for swinging said lever in theopposite direction, said fluid operated means including a cylinder and apiston therein and fluid supply means for said cylinder including avalve and operating means therefor including an element having areas atits opposite sides for the action thereon of fluid pressure, means forcontinuously delivering to the opposite sides of said element pressurefluid from a common source, and means for venting fluid from one side ofsaid element automatically when the pressure from said source builds upabove a predetermined value.

17. A controlling device for an engine driven compressor unit foreffecting, through a variation in the tension of a governor spring, acontrol of engine speed, said controlling device comprising a leverswingable to vary the tension of a governor spring, and actuating meansfor said lever including spring means for swinging the same in onedirection and fluid operated means for swinging said lever in theopposite direction, said fluid operated means including a cylinder and apiston therein and fluid supply means for said cylinder including avalve and operating means therefor including an element having areas atits opposite sides for the action thereon of fluid pressure, means fordelivering to the opposite sides of said element continuously a pressurefluid from a common source, means for venting fluid from one side ofsaid element automatically when the pressure from said source builds upabove a predetermined value, and valve means for venting fluid from saidone side of said element at will.

18. A controlling device for an engine driven compressor unit foreffecting, through a variation in the tension of a governor spring, acontrol of engine speed, said controlling device comprising a leverswingable to vary the tension of a governor spring, and actuating meansfor said lever including spring means for swinging the same in onedirection and fluid operated means for swinging said lever in theopposite direction, said fluid operated means including a cylinder and apiston in said cylinder and controlling means for supplying and ventingfluid relative to said cylinder including a valve and operating meanstherefor including an element having areas at its opposite sides for theaction thereon of fluid pressure, means for delivering compressordischarge pressure freely to one side of said element, means fordelivering compressor discharge pressure in restricted volume to theother side of said element, and a spring loaded relief valve responsiveto the pressure which acts thereon and having provision for theadjustment of the load thereon for precluding the building up ofpressure in excess of a given value at said latter side.

19. A controlling device for an engine driven compressor unit foreffecting, through a variation in the tension of a governor spring, acontrol of engine speed, said controlling device comprising a leverswingable to vary the tension of a governor spring, and actuating meansfor said lever including spring means for swinging the same in onedirection and fluid operated means for swinging said lever in theopposite direction, said fluid operated means including a cylinder and apiston in said cylinder and controlling means for supply and ventingfluid relative to said cylinder including a valve and operating meanstherefor including an element having areas at its opposite sides for theaction thereon of fluid pressure, means for delivering compressordischarge pressure freely to one side of said element, means fordelivering compressor discharge pressure in restricted volume to theother side of said element, a spring loaded relief valve havingprovision for the adjustment of the load thereon for precluding thebuilding up of pressure in excess of a given value at said latter side,and means for venting pressure from said latter side at will having aflow capacity exceeding the flow capacity of said means for deliveringcompressor discharge pressure in restricted volume.

20. In combination, in a controlling device for the unloading means andthe engine speed of an engine driven compressor having means for varyingthe engine speed and means for unloading the compressor, a casingproviding a chamber having opposed flexible walls, means for supplyingcompressor discharge pressure to said chamber, plungers operable by saidwalls, means for subjecting the sides of said flexible walls remote fromsaid chamber to compressor discharge pressure at a restricted rate,means for relieving said sides of pressures in excess of differentpredetermined values below compressor discharge pressure, an enginespeed control element movable in a predetermined direction to reduceengine speed, one of said plungers operable by its coacting flexiblewall to actuate said speed control element in said predetermineddirection, a fluid operated servo mechanism for actuating said controlelement further in said direction, and a control valve operable toeflect compressor unloading and supply of fluid to said servo mechanism,said control valve engageable by the other of said plungers.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 1,096,265 Richards May 12, 1914 2,102,865 Vickers Dec. 21,1937 2,294,410 Lamberton Sept. 1, 1942 2,454,363 Wineman Nov. 23, 1948

